There are plenty of screwdrivers on the market. A conventional screwdriver has a chamber in the handle, which has a notch at one side and is covered by a cap. By opening the cap, screwdriver heads in the chamber are free to take away. The screwdriver heads are secured on a shaft, which then are secured on a threaded cap. The shaft is extending through the cap and connected with a knob. By turning the knob, the shaft is turning simultaneously so that a user may choose a desired head. However, in order to pick up the head, the user has to stretch into the notch with their finger, and the cap is in a loose status, which may be lost.
Another conventional screwdriver has a hole at the rear end of a handle with a cover thereon. A screwdriver head can slide out from the hole. There are some shortcomings of this design. One is that the cover may be misplaced easily.